Many industrial applications require the use of a transducer device to monitor the rotational speed or angular displacement of a rotational shaft that is also provided at one end with a rotary gland or seal through which a liquid or gas is introduced into a passageway within the shaft. With previously known seal and rotational transducer components, this dual requirement of motion sensing and gas or liquid induction dictates the use of separate transducer and seal units, each of which included its own bearings, housing and rotation resisting means. Furthermore, the necessity of mounting the seal at the center of an accessible end of the shaft often requires the use of a more expensive type of transducer unit than would be needed if the latter unit could occupy that position. Additionally, presently available transducer units otherwise suitable for such applications are often relatively complex and delicate and hence are not well-suited for convenient servicing in the field.